Design rules for high yield in the scribe and separate processes in the manufacture of liquid crystal devices (LCDs) require a ratio of 5:1 (area to substrate thickness) for removing a section of one substrate relative to another when a contact ledge is required on the device. The present invention avoids this limitation and thereby eliminates the waste of expensive processed silicon substrate as a non-functional area to maintain this required ratio.
Silicon real estate is the most expensive component in a Liquid Crystal On Silicon (LCOS) device. In conventional die layouts, the necessary ledge dimension for a 0.7 mm glass counter-electrode plate would be 3.5 mm. Typical wedge bonding requirements place this ledge dimension at less than 1 mm. Therefore, even in the most lenient of designs for the bond pad ledge, an additional non-functional area of 2.5 mm multiplied by the width of silicon is required just to satisfy the requirements for glass scribing and removal.